Add support for Windows (#492)

This adds support for Windows.
The in-language path separator is still `/`, to ensure Pkl programs are cross-platform.

Log lines are written using CRLF endings on Windows.
Modules that are combined with `--module-output-separator` uses LF endings to ensure
consistent rendering across platforms.

`jpkl` does not work on Windows as a direct executable.
However, it can work with `java -jar jpkl`.

Additional details:

* Adjust git settings for Windows
* Add native executable for pkl cli
* Add jdk17 windows Gradle check in CI
* Adjust CI test reports to be staged within Gradle rather than by shell script.
* Fix: encode more characters that are not safe Windows paths
* Skip running tests involving symbolic links on Windows (these require administrator privileges to run).
* Introduce custom implementation of `IoUtils.relativize`
* Allow Gradle to initialize ExecutableJar `Property` values
* Add Gradle flag to enable remote JVM debugging

Co-authored-by: Philip K.F. Hölzenspies <holzensp@gmail.com>

.circleci/jobs/GradleCheckJob.pkl

@@ -15,9 +15,11 @@
 //===----------------------------------------------------------------------===//
 extends "GradleJob.pkl"
 
-import "package://pkg.pkl-lang.org/pkl-pantry/com.circleci.v2@1.1.0#/Config.pkl"
+import "package://pkg.pkl-lang.org/pkl-pantry/com.circleci.v2@1.1.2#/Config.pkl"
 
-javaVersion: "11.0"|"17.0"|"21.0"
+javaVersion: "17.0"|"21.0"
+
+os = "linux"
 
 steps {
   new Config.RunStep {
@@ -27,9 +29,17 @@ steps {
 }
 
 job {
-  docker {
-    new {
-      image = "cimg/openjdk:\(javaVersion)"
+  when (os == "linux") {
+    docker {
+      new {
+        image = "cimg/openjdk:\(javaVersion)"
+      }
     }
   }
+  when (os == "windows") {
+    machine {
+      image = "windows-server-2022-gui:current"
+    }
+    resource_class = "windows.large"
+  }
 }